I am often asked to give seminars help Christians tell their friends, family, and work colleagues about Jesus. Over the last decade, the nature of the questions afterwards has increasingly changed. Whereas the questions previously concerned the method of evangelism—e.g., “How do I bring up my faith in a conversation?”—the questions now relate to the ethics of evangelism—e.g., “As a boss, am I allowed to tell my workers about Jesus?”

This has been an under-explored area of Christian evangelism. Most books on evangelism have a brief treatment on the definition of evangelism, something on the biblical warrant for evangelism, and then a suggestion of methods of evangelism. But there is very little on the ethics of evangelism. Can a doctor tell her patient about Jesus? What about a school teacher to her students? What about an uncle to his niece?

Elmer John Thiessen fills this gap with his latest book The Scandal of Evangelism: A Biblical Study of the Ethics of Evangelism. This is familiar territory for Thiessen. He previously taught philosophy for 36 years at Medicine Hat College in Alberta, where he was open with students about his Christian faith. His earlier book, The Ethics of Evangelism: A Philosophical Defense of Proselytizing and Persuasion (Downers Grove, IL: InterVarsity Press, 2011) was written for both Christian and non-Christian audiences.

The audience of this book, The Scandal of Evangelism, is the Christian reader. The goal is twofold: (1) to provide a biblical grounding for a Christian ethics of evangelism, and (2) to apply this to contemporary examples. These two aims divide the book into two halves.

The first half of the book achieves the first aim by providing a biblical theology of evangelism. Thiessen spends some time on what I call the prolegomena of evangelism. What is the gospel? What is the relationship between word and deed? What is the relationship between evangelism and mission? What is the relationship between personal salvation and kingdom membership? Do I proclaim the gospel for conversion to make disciples or to grow disciples? Thiessen’s treatment here is both welcome and thorough.

Thiessen then surveys what evangelism looks like in the Bible, giving particular attention to the New Testament. From this, he generates ethical guidelines for evangelism. The most useful guideline is the Golden Rule: “Evangelize others as you yourself would like to be evangelized” (p. 115). I also appreciate the guidelines that deal with the motivation for evangelism (pp. 129–30). After all, this is the heart of Christian ethics—not so much what we do, but who we are when we do it.

The second half of the book applies these guidelines to four specific, contemporary situations: (1) evangelism of children; (2) evangelism in professional life, with particular attention to the academy; (3) evangelism and humanitarian aid; and (4) the ethics of proselytism, with particular attention to “sheep stealing”—i.e., evangelizing Christians from another church, denomination, or tradition.

Once again, I found Thiessen’s treatment to be highly informed—benefitting both from research and his personal experiences—with nuanced and balanced conclusions. Whether or not you agree with his conclusions, you will always grant that he gives the other side a fair hearing and then adequately justifies his own conclusions.

This book is actually more than a book on the ethics of evangelism. Thiessen also gives us theological treatments on important subjects, such as freedom, coercion, work, and social action. He also gives us useful categories for navigating the ethical minefield of evangelism, e.g., a “sliding scale” for evaluating the relationship between humanitarian aid and evangelism (pp. 191–93). At other times, the book is an apology, i.e., a defense—of Christian evangelism.

In the end, the crux of the ethical debate regarding evangelism is the notion of coercion. At various sections of the book, Thiessen does a great job of giving us a philosophical and theological analysis of coercion—for example, distinguishing between it and constraint (p. 187).

If I have concerns, they are minor. First, most books on evangelism pit the work of the Holy Spirit against human effort. For example, “Ultimately, any success we might have in evangelism is the work of God’s Spirit, and not the result of our own abilities” (p. 86). But can’t it be a both-and rather than an either-or, especially if the Spirit is the supernatural, personal agent, and the human evangelist’s efforts are the natural, instrumental means? Second, at a style level, Thiessen often says, “First …” and then I can’t find a “Second …” and “Third …”! But, like I said, these are very minor concerns.

Overall, this is a welcome addition to the canon of books on evangelism. This book covers much territory on the prolegomena of evangelism, which many other survey books do not address. Its most valuable contribution is that it fills a gap—on the ethics of evangelism—which has been surprisingly untreated until now. It is timely, because our post-Christendom 21st century world is very concerned about issues of power, violence, and coercion. Christians will need all the tools they can get to navigate this new world. Finally, this book is both highly informed by academia and personal experience. I recommend it highly.